The invention pertains to methods of cleaning surfaces of copper-containing materials. In particular embodiments, the invention pertains to semiconductor processing methods of forming openings to copper-containing substrates.
Copper has a relatively high conductance compared to many other elements, and accordingly can be desired for utilization as a wiring layer in various circuitry applications. For instance, in semiconductor processing applications, it can be desired to provide copper wiring layers as electrical paths to various integrated circuit components.
A difficulty in utilizing copper in semiconductor processing applications is that it can be difficult to clean. For instance, copper-containing materials will frequently have a surface to which electrical connection with other conductive components is ultimately to occur. Formation of such electrical connection will frequently involve providing a conductive material over the surface of the copper-containing material. The conductive material is intended to physically contact the surface of the copper-containing material to form an electrical connection with the copper-containing material. However, if the surface of the copper-containing material is partially or entirely covered with debris, the physical connection of the conductive material and copper surface can be impaired. Such impairment can lead to attenuation of electrical current passing between the copper-containing layer and the conductive material formed thereover.
It would be desirable to develop improved methods of cleaning copper-containing surfaces to remove debris from over the surfaces prior to forming conductive materials thereon.
In one aspect, the invention encompasses a semiconductor processing method of cleaning a surface of a copper-containing material by exposing the surface to a mixture having an acidic pH and comprising NO3xe2x88x92, Fxe2x88x92 and one or more organic acid anions, where at least some of the organic acid anions contain carboxylate groups.
In another aspect, the invention includes a semiconductor processing method of forming an opening to a copper-containing material within a substrate. The substrate contains a semiconductor material and has a first opening. A copper-containing material is provided within the first opening and a mass is formed over the substrate and over the copper-containing material. The mass comprises at least one of an oxide barrier material and a dielectric material. A second opening is etched through the mass into the copper-containing material. A surface of the copper-containing material defines a base of the second opening and is referred to as a base surface. The base surface of the copper-containing substrate is at least partially covered by at least one of a copper oxide, a silicon oxide or a copper fluoride. The base surface is cleaned with a cleaning solution having an acidic pH and comprising nitric acid, hydrofluoric acid and one or more organic acids. At least some of the organic acids have one or more carboxylic acid groups. The cleaning removes at least some of the at least one of a copper oxide, a silicon oxide and a copper fluoride from the base surface.